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Recovery Strategy for the Eastern Prickly Pear Cactus (Opuntia humifusa) in Canada

8. Critical Habitat Identification

Critical habitat for the Eastern Prickly Pear Cactus is identified for three extant, native populations of the species: two in Point Pelee National Park and one in Fish Point Provincial Nature Reserve on Pelee Island.

8.1 Approaches Used to Identify Critical Habitat

The Ecological Land Classification (ELC) vegetation types where Eastern Prickly Pear Cactus naturally occurs have been used to identify its critical habitat. However the spatial arrangement and the amount of each vegetation type are not fixed. This is because these vegetation types occur along a dynamic shoreline where natural disturbance regimes make them shift in space and time. In degraded, secondary successional habitats and areas where the vegetation has succeeded beyond optimal growing conditions for Eastern Prickly Pear Cactus, the species' critical habitat is identified using an occupancy-based approach. This provides an opportunity for recovery work to be undertaken to restore habitat conditions appropriate to the species rather than requiring the preservation of the habitat that is currently present and that may not continue to support cacti in the future.

Eastern Prickly Pear Cactus critical habitat descriptions and mapped delineations will be refined as new information or improved techniques for critical habitat identification become available.

8.2 Maps of Eastern Prickly Pear Cactus Critical Habitat

Precise geographic locations for Eastern Prickly Pear Cactus critical habitat are not presented in this recovery strategy, and will not be presented in any action plan, to protect the species from the threat of collection. Under advice from the Recovery Team, the SRA, and the chair of COSEWIC, precise geographic locations for critical habitat will not be presented in the Recovery Strategy in order to protect the species from the threat of harvesting or wilful destruction of individuals and their habitat.

The Eastern Prickly Pear Cactus critical habitat map for Point Pelee National Park is housed at Point Pelee National Park, Leamington, Ontario, and in the Parks Canada Ontario Service Centre in Cornwall. ELC mapping and mapping of all Eastern Prickly Pear Cactus occurrences at Fish Point Provincial Nature Reserve are housed at the Ontario Parks, Southwest Zone office in London, Ontario.

8.3 Critical Habitat Within Point Pelee National Park

Within the boundaries of Point Pelee National Park, as identified on the National Topographic System (NTS) map 40G/15 (edition 7, printed 2001), part of the critical habitat for the Eastern Prickly Pear Cactus is identified as the three primary successional Lake Erie Sand Spit Savanna ELC vegetation types in which the cactus is currently found at this site (Lee et al. 1998, Lee 2004, Dougan & Associates 2007). These types are:

  • Little Bluestem-Switchgrass-Beachgrass Open Graminoid Sand Dunes,
  • Hoptree Shrub Sand Dunes and
  • Red Cedar Treed Sand Dunes.

The remaining parts of the species' critical habitat are identified as a circle with a radius of 25 m from the centre point of each of these two groups of Eastern Prickly Pear Cactus microsites:

  • those found in secondary successional ELC vegetation types that are degraded Lake Erie Sand Spit Savannas, and
  • those found in sites that have succeeded beyond optimal conditions for Eastern Prickly Pear Cactus, such that the cactus is considered to be a relict of past conditions.

The 25 m radius used was chosen to minimize shading of Eastern Prickly Pear Cactus sites that might result from the placement of new infrastructure, as these cacti grow optimally with 50 to 70 percent light availability.

8.4 Critical Habitat within Fish Point Provincial Nature Reserve

Within Fish Point Provincial Nature Reserve, as identified on the NTS map 40 G/15, critical habitat for the Eastern Prickly Pear Cactus is identified as the entire area within the Red Cedar Treed Sand Dunes ELC vegetation type, the primary successional Lake Erie Sand Spit Savanna ELC vegetation type in which Eastern Prickly Pear Cactus is currently found at this site (Lee et al. 1998, Lee 2004, Dobbyn 2006).

8.5 Parts of Occupied Habitat not Included in the Species' Critical Habitat

Existing anthropogenic features, including, but not limited to, parking lots, roads, trails, footpaths, cemeteries and septic fields, are excluded from the species' critical habitat because they are not suitable for supporting the species. Areas where all Eastern Prickly Pear Cactus microsites have been planted or transplanted, where records remain unverified or where its location or origin is uncertain, are not considered critical habitat. Two areas within Point Pelee National Park currently fit within this category. Complete geographical descriptions of these two areas are housed at Point Pelee National Park. Elsewhere, Eastern Prickly Pear Cactus that remains extant has been determined to be planted at:

  • Rondeau Provincial Park, Municipality of Chatham-Kent
  • Howard Township Cemetery, Municipality of Chatham-Kent
  • Turkey Point, Norfolk County
  • The south barrier beach of Big Creek Marsh, Port Rowan, Norfolk County
  • Harwich Township Cemetery, Municipality of Chatam-Kent
  • in various private gardens throughout the range

No areas at Long Point are identified as critical habitat, as records of the locations are not specific and cannot be verified.